Salvadoeb la gbassa



(No Model.)

S. LA GRASSA.

KEY BOTTOM POR MANOS.

NO. 347,356. Patented Aug. 17, 1886.

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UNITED STATES PATENT OFFICE.

SALVADORE LA GRASSA, OF NEV YORK, N. Y.

KEY-BOTTOM FOR PIANOS.

SPECIFICATION forming part of Letters Patent No. 347,356, dated August 17, 1886, Application filed November 20, 1885. Serial No. 183,424. (No model.)

To all tlf/tom it 77mg/ concern:

Be it known that I, Sinin-moan LA GRAssA, of the city and county of New York, in the State oi New York, have invented a new and useful Improvement in Key Bottoms for Pianos and Similar Instruments, of which the following is spccilication.

In the construction of upright and grand pianos the l'rame on which the keys are supported side by side is usually secured to a broad flat wood plank, which is attached at the ends to the under sides of arms projecting outward from the case, and is technically known as the key-bottom. By changing seasons and the dilierent and changing conditions of the atmosphere as to moisture this wood key-bottom is very liable to bend or warp both lengthwise and crosswise, and the keys are thereby thrown out 0f position to such an extent as to greatlyimpair theinstrument and interfere with proper touch and exeeution in playing'.

The object ol" my invention is t0 overcome the objections which are inherent in a keybottom made entirely of wood, and to provide a key-bottom which will maintain its true flat surface under any atmospheric changes and always hold the key-frame and keys in proper position.

The invention consists, essentially, in a keybottom of cast meta-l constructed in a novel manner, hereinafter dcscribcd,and pointed out in the claims.

In the accompanying drawings, Figure l is a transverc section ol" a key-bottom embodying my invention and a key-frame supported thereon. Fig. 2 is a longitudinal section ol the bottom and frame, and Figs. 3 and 4 are respectively a top and inverted plan of the key-bottom alone.

Similar letters of reference designate correspondings parts iu all the figures.

A designates the key-bottom, and B the usual key-frame supported thereon, and composed o'f the front and back bars, b b', and cross-bars Z, and the bar b, whcreon the keys are fulcrumed.

The key-bottom consists ol' a cast-metal plate or frame, preferably having a truly liat upper surface, which is continuous so far as is necessary to support the several bars or rails ofthe key-frame B.

For the sake of lightness I have represented openings a at those parts of the key-bottom where no parts of the key-frame rest, and such openings may be closed boards or wood panels C, which may be held in place by screws inserted through holes s, in order to prevent dust from rising through the key-bottom and into the piano.

I have shown the plate A as provided on its under side with longitudinal ribs a, which, as shown, are arranged in pairs ou opposite sides of the openings a, and serve to prevent the plate or bottom from bending or warping in a direction lengthwise thereof. I have also shown the plate or bottom as having on its under side transverse ribs which also eX- tend in pairs between the openings a and join the ribs a.

The key-bottom, when constructed as above described, will be very stift" and yet light, and its upper surface, which supports the keyframe, will be maintained in its trulyat condition and will not be bent or twisted by any atmospheric changes.

I have represented the vkey-bottom as provided with holes s', for the insertion of screws from its under side to secure the key-frame B in place upon it, and with holes 8"', for the insertion ot' screws into the arms of the pianocase for securing the key-bottom thereto.

I have shown the key-bottom as surrounded on the front and ends by a molding, c, as is usual with wood key-bottoms.

XVhat I claim as my invention, and desire to secure by Letters Patent, is-

l. A key-bottom for pianos or similar instruments, formed of metal and provided with stiffenin g ribs or iianges, substantially as herein described.

2. A cast-metal key-bottom for pianos or similar instruments, consisting of a plate having upon its under side longitudinal strengthening-ribs, substantially as herein described.

3. A cast-metal key bottom for pianos or similar instruments, consisting of a plate having upon its under side longitudinal and transverse strengthening-ribs, substantially as herein described.

IOC)

4. A cast-metal keybottom for pianos or vG.. The cast-metal keyhottomA, having a similar instruments, having a fiat upper surzit upper surface with openings a, and panels face for the support of a key-frame and hzw- C,covering the openings, andhavingon the un- 15 ing strengthening-ribs upon its underside,sub der side strengthening-ribs a a?, substantially 5 stantially as herein described. as herein described.

5. A cast-metal keybottom for pianos or f similar instruments, having its upper surface SALVADORE LA GRASSA.

fiat and continuous or unbroken in those portions on which the key-frame is to rest, and Witnesses:

ro having openings between such portions, and C. HALL,

strengthening-ribs 011 its under side, substan- FREDK. HAYNEIELv tially as herein described. 

